distinctive white bridle or collar that separates it from Sooty tern is
generally easily visible in flight. Bahrain has one rather dubious
record of Sooty Tern - Inexperience of the observers (of which it has
to be said I was one but I was new to birding then) with Bridled terns
and oiled up birds I now think, having seen similar since, were the
cause of the misidentification.